<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title>盒子的定位显示</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" type="text/css" media="screen" href="main.css" />
    <script src="main.js"></script>
    <style type="text/css">
    
    .one{
			 	 height: 300px;
			 	 width: 577px;
			 	 border: 1px solid  green;
			 	 margin: 0 auto;

			 	 position: relative;
			 }

			 .two{
			 	 width: 100px;
			 	 height: 100px;
			 	 border: 1px solid yellowgreen;
			 	 position: absolute;
			     left: 50%;
			     margin-left: -50px;
			     /* bottom:0; */
			 	 
			 

    </style>
</head>
<body>
    <div class="one">

        <div class="two">

        </div>
    </div>
</body>
</html>